I would like to think in a way that investment in general, and the real estate investment, start with a solid economic reason - "Why do you Invest, where you invested".To elaborate on below - Vegas is a great example where no real economic driver exists and when you invest there, you should be aware that is a highly volatile market (side note: i both 2 properties there in 2011 and 2012 and i sold both this year) and you should pay an extra attention and be prepare to reposition capital.It's clear, if you invest in Vegas or Orlando (just 2x entertainment cities) you will expect ups and downs and you need to position yourself with extra reserves and extra caution if you are planning to stay in these market for long term. 

I mean by safest is on the volatility, for example STRs have many different factors, seasons of the year, local government regs and much more.

You're pulling from a work force of highly volatile people, who're tasked w/ doing an extremely physically and mentally draining job (in whatever weather mother nature provides for the day). 

Quote from @Chris Seveney: @Leland HertigWe are lending (and getting) 15% +3 pts on land at this time.Land financing is going to be very expensive due to its illiquid nature and volatility in down markets.  

Personally, I love the idea of putting more cash down on a deal if it is going to drive up my cash yield, but I never put down too much cash that it would push my COC under 8%.In my calculations, I always run the repairs at 4% and CAPEX at 6% unless the property is in poor condition or in a bad neighborhood (in which case I'm hesitant anyways to buy a rental property because of a possible volatile vacancy rate.)

The difference is the volatility of owning multiple units versus a single house is usually a lot lower.

Use caution when borrowing against your stock portfolio, especially if it's a high volatility portfolio comprised of individual companies.

There is no stock account that gives the leverage real estate does, at as low interest rate real estate does, at as low risk/ volatility real estate does. 

But hot markets are inherently more volatile.

Time and time again, I hear that the military (Navy, Army, Air Force, and Coast Guard) are constantly moving people into the area which means that compared to other markets, we are stabilized and don't have as much volatility as other markets.